Transportation Safety Board of Canada
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  AVIATION REPORTS - 1999 - A99P0108

The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

Aviation Investigation Report
Midair Collision
Between Cessna 177RG Cardinal C-GWYY
and Mooney M20C C-GASL
Penticton, British Columbia
20 August 1999

Report Number A99P0108

Synopsis

A Mooney M20C was returning to the Penticton, British Columbia, airport from the northwest after a local visual flight rules flight with the pilot and three passengers on board. The aircraft remained west of the extended runway 34 centreline until turning eastbound onto a track that would intersect the departure path of runway 34. About this time, a Cessna 177RG at the Penticton airport taxied out for a visual flight rules departure, northbound to Valemount, with only the pilot on board. The pilot of the Cessna 177RG advised the Penticton flight service station that he was ready to depart. The flight service station specialist acknowledged and recorded the departure time as 1135 Pacific daylight time. At about 1136, the Cessna 177RG and the Mooney M20C collided in-flight about 0.9 nautical mile from the departure end of runway 34. Both aircraft were destroyed and crashed within the city of Penticton. All five occupants were fatally injured; no other injuries occurred. At the time of the accident, the weather was sunny with unrestricted visibility, little cloud, and calm wind.

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Table of Contents

  1. 1.0 Factual Information
    1. 1.1 History of Flight
    2. 1.1.1 Mooney M20C
    3. 1.1.2 Cessna 177RG
    4. 1.1.3 Penticton Flight Service Station
    5. 1.2 Injuries to Persons
    6. 1.2.1 Mooney M20C
    7. 1.2.2 Cessna 177RG
    8. 1.3 Damage to Aircraft
    9. 1.3.1 Mooney M20C
    10. 1.3.2 Cessna 177RG
    11. 1.4 Other Damage
    12. 1.5 Personnel Information
    13. 1.5.1 Mooney M20C
    14. 1.5.2 Cessna 177RG
    15. 1.5.3 Penticton FSS Specialist—Radio Position
    16. 1.5.4 Penticton FSS Specialist—Support Position
    17. 1.5.5 Penticton FSS Specialist—Downstairs Position
    18. 1.6 Aircraft Information
    19. 1.6.1 Mooney M20C
    20. 1.6.2 Cessna 177RG
    21. 1.7 Meteorological Information
    22. 1.8 Aids to Navigation
    23. 1.9 Communications
    24. 1.9.1 Penticton FSS
    25. 1.9.2 Pilot Communication Responsibilities
    26. 1.9.3 Communication Summary
    27. 1.10 Airport Information
    28. 1.11 Flight Recorders
    29. 1.12 Wreckage and Impact Information
    30. 1.12.1 Mooney M20C
    31. 1.12.2 Cessna 177RG
    32. 1.12.3 Wing Wreckage Site
    33. 1.13 Medical Information
    34. 1.14 Fire
    35. 1.15 Survival Aspects
    36. 1.16 Tests and Research
    37. 1.16.1 Collision Geometry
    38. 1.16.2 Cessna 177RG
    39. 1.16.3 Mooney M20C
    40. 1.16.4 Constant Relative Bearing
    41. 1.17 Other Information
    42. 1.17.1 Visual Limitations from Aircraft Design
    43. 1.17.2 Physiological Limitations of the Human Eye
    44. 1.17.3 Midair Collision Defences
    45. 1.17.4 Statistics
    46. 1.17.5 Circuit Procedures—Uncontrolled Aerodromes
    47. 1.17.6 Communication Procedures—Uncontrolled Airports
  2. 2.0 Analysis
    1. 2.1 General
    2. 2.2 Circuit Procedures and Communications Procedures
    3. 2.2.1 Mooney M20C
    4. 2.2.2 Cessna 177RG
    5. 2.2.3 Penticton Flight Service Station
    6. 2.3 Control Tower
    7. 2.4 Operational Circumstances
  3. 3.0 Conclusions
    1. 3.1 Findings as to Causes and Contributing Factors
    2. 3.2 Findings as to Risk
    3. 3.3 Other Findings
  4. 4.0 Safety Action
    1. 4.1 Action Taken
  5. 5.0 Appendices
    1. Appendix A—Glossary
  6. Figures
    1. Figure 1—Mooney M20C flight path
    2. Figure 2—Collision flight paths
    3. Figure 3—Standard left-hand circuit pattern

1.0 Factual Information

1.1 History of Flight

1.1.1 Mooney M20C

The Mooney M20C, hereafter called "the Mooney", departed the Penticton, British Columbia, airport from runway 16 at 1052 Pacific daylight time (PDT)(1) on a local visual flight rules (VFR) sightseeing flight and was expected to return in about 45 minutes.

At 1127, the pilot re-established communications with the Penticton flight service station (FSS) on the mandatory frequency (MF) of 118.5 megahertz and reported that he was east of the airport at 5500 feet inbound for landing. The Penticton FSS issued an airport advisory indicating that runway 34 was the preferred runway. The pilot acknowledged runway 34. At 1130, he advised that he was proceeding northwest toward Naramata—8 nautical miles (nm) north of the airport—for his descent. At 1133, the pilot reported by Naramata. About one minute later, he advised that he was proceeding south along the west side of Okanagan Lake toward Penticton. The initial contact was the only time the pilot reported his altitude to the FSS.

The West Bench section of Penticton is within the Penticton MF area, on the west hillside of the Okanagan valley, facing east and overlooking the city.

Figure 1 - M20C flight path

Figure 1 - M20C flight path

As the aircraft flew south along the west shoreline, witnesses reported that it flew by the Redwing subdivision and the West Bench area at a low altitude, close enough for people on the ground to see the people inside. A witness viewed the aircraft from the east and described the flight profile to be below the level of a landmark on the hillside. The landmark is about 400 feet above the elevation of the airport. Near the southwest corner of Okanagan Lake, abeam the West Bench area, the aircraft entered a left turn. This turn took the aircraft on a southeasterly heading parallel to and north of a section of the canal that passes through the city and connects Okanagan Lake with Skaha Lake on the south side of Penticton. On this heading, the flight path intersected the departure path of runway 34, close to the Penticton non-directional beacon (NDB).

1.1.2 Cessna 177RG

The pilot of the Cessna 177RG, hereafter called "the Cessna", had filed a flight plan with the Penticton FSS for a VFR flight north to Valemount for one person on board. The flight plan included an estimated time en route of 1 hour 45 minutes and 4.5 hours of fuel duration. An altitude was not specified.

At 1129, the pilot called the Penticton FSS on the MF and advised that he was taxiing out at Penticton for a northbound departure to Valemount on a VFR flight plan. The Penticton FSS issued an airport advisory indicating that two aeroplanes (including the Mooney) were inbound for landing on runway 34 and that one helicopter was inbound for a helipad. The pilot acknowledged the advisory and proceeded to taxi.

At 1134, after the helicopter and one of the two aeroplanes had landed, the pilot of the Cessna called the Penticton FSS on the MF and advised that he was ready for take-off on runway 34. The pilot did not request a traffic update. The FSS acknowledged the transmission, and the Cessna departed at 1135.

1.1.3 Penticton Flight Service Station

An FSS is a ground station established to provide air traffic advisory services, flight information services, and emergency assistance services for the safe movement of aircraft. The FSS specialist is not an air traffic controller and is not responsible for air traffic separation. The Penticton FSS uses the former air traffic control tower, which provides the specialists a clear view of the airport and the surrounding area in all directions. Three operational FSS specialists were on duty at the time of the accident. Two specialists were in the cab: one staffing the Radio position and one staffing the Support position. The third specialist was staffing the Downstairs position in the main FSS office.

Communication records show that the Penticton FSS had communicated with four aircraft on the MF and with an airport staff vehicle on the ground control frequency in the 11 minutes before the accident. In the 2 to 3 minutes before the accident, the only communications were with the two accident aircraft on the MF; there were no communications on the ground control frequency. At the time of the collision, one operations-related telephone call was in progress between the Support position and the Downstairs position. Both specialists in the cab reported their workload to be light during the 30 minutes before the collision.

When the Cessna taxied for departure, the pilot was advised of and acknowledged three aircraft inbound to the airport. During the next five minutes, the Penticton FSS received five transmissions from the inbound Mooney and replied three times before the Cessna departed. The pilot of the departing Cessna did not request a traffic update, nor was he directly advised of the one remaining aircraft inbound from the northwest (the Mooney). The FSS specialist did not make a direct transmission to the arriving Mooney to advise of the Cessna departing from runway 34 or to request a position update and circuit-joining intentions to determine if a conflict might exist; the Flight Service Station Manual of Operations (FSS MANOPS) does not require these actions if the FSS operator believes there are no conflicts. Because both pilots were, or should have been, operating on the same frequency, they should have been aware of the other's position and intentions. No other traffic was reported in the Penticton MF area at the time.

1.2 Injuries to Persons

1.2.1 Mooney M20C

  Crew Passengers Total
Fatal 1 3 4
Serious - - -
Minor/None - - -
Total 1 3 4

1.2.2 Cessna 177RG

  Crew Passengers Total
Fatal 1 - 1
Serious - - -
Minor/None - - -
Total 1 - 1

1.3 Damage to Aircraft

No indication was found of a malfunction or pre-existing mechanical defect in either aircraft. Both aircraft apparently followed their respective flight paths and profiles in a controlled fashion until the in-flight collision. The departing Cessna was seen to be climbing normally following the extended runway centreline, and the Mooney was seen flying at low level in a smooth left-hand turn in the seconds before the in-flight collision. After the aircraft collided, the damage rendered both aircraft uncontrollable.

1.3.1 Mooney M20C

The right wing, outboard of the main landing gear, and the vertical stabilizer were severed from the aircraft. Both pieces struck the ground within a fenced area at the city waste treatment plant located on a bearing of 162 degrees magnetic (ºM), 1330 feet from the Penticton NDB tower. The body of the aircraft struck the ground in a factory work yard located on a bearing of 132M, 1970 feet from the Penticton NDB tower and 4580 feet north of the departure end of runway 34. The collision and the ground impact destroyed the aircraft. No fire occurred.

The aircraft journey logs and the aircraft documents had not been on board the aircraft and were obtained, along with the pilot's personal logbook, from his family.

1.3.2 Cessna 177RG

An outboard section of the right wing was severed during the midair collision and struck the ground near the severed wing and vertical stabilizer of the Mooney. The body of the aircraft struck the ground in a vacant parking lot on a bearing of 210ºM, 440 feet from the Penticton NDB tower. The aircraft caught fire at impact and was virtually consumed except for the tail section. However, the pilot's personal flight log and the aircraft journey log containing the aircraft documents were recovered intact from the wreckage.

1.4 Other Damage

The two aircraft created small impact craters in the asphalt surface at their respective accident sites. There was some fire damage to the grass field adjacent to the site of the main Cessna wreckage.

1.5 Personnel Information

1.5.1 Mooney M20C

Age 33
Pilot Licence Commercial restricted to Private Pilot privileges
Medical Expiry Date 01 July 2000
Total Flying Hours 1173
Hours Last 90 Days 59
Hours on Type Last 90 Days 3.2

The pilot had held a Canadian Commercial Pilot Licence—Aeroplane (CPL-A) since 29 July 1987; however, his licence was valid for Private Pilot Licence—Aeroplane (PPL-A) privileges only, because more than 12 months had passed since his last civil aviation medical examination. His licence included a Group 2 instrument rating valid until 01 September 2001. His personal logbook indicated that he had flown 3.2 hours on this particular aircraft within the previous 12 months. His logbook also indicated that he had flown 103 hours on a similar aircraft and 55 hours on a light twin-engine aircraft and that he had completed 6 trips to Penticton within the previous 12 months.

1.5.2 Cessna 177RG

Age 56
Pilot Licence Private Pilot—Aeroplane
Medical Expiry Date 01 May 2000
Total Flying Hours 568
Hours Last 90 Days 4.6
Hours on Type Last 90 Days 4.6

The pilot held a Canadian PPL-A since 13 December 1981. His licence included a night endorsement obtained 30 October 1994. His personal logbook indicated he had accumulated 362 hours of flight time on this particular aircraft or model since 15 October 1989 and that he had flown 46 hours within the previous 12 months. He was a resident of Penticton from 1983 until 1991, when he relocated to Valemount; however, he continued to fly out of Penticton.

1.5.3 Penticton FSS Specialist—Radio Position

FSS Position Air/Ground 2 (Radio)
Assisted by one other FSS specialist
Qualification Classification: RO-000-03 FSS specialist
Experience
Basic Training 1975
Worked in the Penticton FSS since March 1995
Onsite Unit Qualification April 1995
FSS Refresher Training February 1987, February 1992, August 1997,
February 1998, December 1998
Hours on Duty Prior to Incident 5.6
Hours off Duty Prior to Work Period 10.9

This specialist was trained and qualified to work as an operational FSS specialist at the Penticton airport. According to the Penticton FSS shift schedule, he was working his sixth of seven shifts scheduled and had been on duty for 5.6 hours before the accident occurred.

1.5.4 Penticton FSS Specialist—Support Position

FSS Position Support (provides support to Radio position)
Qualification Classification: RO-000-03 FSS specialist
Experience
Basic Training 1967
Worked in the Penticton FSS since March 1995
Onsite Unit Qualification May 1995
FSS Refresher Training February 1988, January 1992, February 1998,
December 1998
Hours on Duty Prior to Incident 1.1
Hours off Duty Prior to Work Period 11.1

This specialist was trained and qualified to work as an operational FSS specialist at the Penticton airport. According to the Penticton FSS shift schedule, he was working his third of six scheduled shifts and had been on duty for 1.1 hours before the accident occurred.

1.5.5 Penticton FSS Specialist--Downstairs Position

The third FSS specialist was working in the main FSS office and was not involved in providing information to the accident aircraft. This position does not normally monitor the MF at Penticton when more than one FSS specialist is on duty and the Radio and Support positions are in operation. He was not monitoring the Penticton MF at the time of this accident.

1.6 Aircraft Information

1.6.1 Mooney M20C

Manufacturer Mooney Aircraft Company
Type and Model M20C
Year of Manufacture 1962
Serial Number 2225
Certificate of Airworthiness 21 April 1992
Total Airframe Time 3163 hours
Engine Type (number of) Avco Lycoming O-360-A1D (1)
Propeller Hartzell HC-CY2K-1BF
Maximum Allowable Take-off Weight 2575 pounds
Recommended Fuel Type Avgas 100 LL
Fuel Type Used Avgas 100 LL

The Mooney is a single-engine, four-place aeroplane capable of cruising flight at 130 knots calibrated airspeed. The aircraft is a conventional configuration with a low wing and retractable tricycle landing gear. Standard equipment includes one fixed landing light mounted on the nose of the aircraft below the propeller hub. Optional wing-tip strobe lights were installed and serviceable. It could not be determined whether any of the external aircraft lights were on at the time of the accident.

The aircraft's wings were red (top and bottom), and the fuselage was red (bottom) and white (top).

The weight and balance of the Mooney at take-off from Penticton was estimated to have been within certificated limits. The aircraft weight was calculated to be approximately 2245 pounds when it taxied out for take-off. The aircraft contained about 110 pounds of fuel (total capacity was 288 pounds), and the pilot and the three passengers weighed an estimated 600 pounds.

An examination of the aircraft and engine maintenance records and other documentation revealed nothing remarkable. The aircraft was certificated, equipped, and maintained in accordance with existing regulations and approved procedures.

1.6.2 Cessna 177RG

Manufacturer Cessna Aircraft Company
Type and Model 177RG
Year of Manufacture 1976
Serial Number 177RG1101
Certificate of Airworthiness 29 June 1990
Total Airframe Time 2562.7 hours
Engine Type (number of) Avco Lycoming IO-360-A1B6D (1)
Propeller McCauley B2D34C207
Maximum Allowable Take-off Weight 2800 pounds
Recommended Fuel Type Avgas 100 LL, Avgas 100
Fuel Type Used Avgas 100 LL

The Cessna Cardinal is a four-place, single-engine aircraft capable of cruising flight at 142 knots indicated airspeed. The aircraft is a conventional configuration, with a cantilevered high wing and retractable tricycle landing gear. Standard equipment includes one fixed landing light and one fixed taxi light mounted on the nose of the aircraft, below the propeller hub. Optional wing-tip strobe lights were installed and serviceable. It could not be determined whether any of the external aircraft lights were on at the time of the accident.

The aircraft was predominantly white with red trim.

The weight and balance of the aircraft at take-off from Penticton was estimated to have been within certificated limits. The aircraft weighed an estimated 2275 pounds when it taxied out for take-off. The aircraft contained 200 pounds of fuel and 50 pounds of baggage; the pilot's weight was reported to be 210 pounds.

An examination of the aircraft and engine maintenance records and other documentation revealed nothing remarkable. The aircraft was certificated, equipped, and maintained in accordance with existing regulations and approved procedures.

1.7 Meteorological Information

The Penticton 1100 regular weather observation taken by the Penticton FSS was as follows: wind 140 degrees true (ºT) at 2 knots, visibility 15 statute miles or greater, a few clouds at 5500 feet above ground level (agl), a few clouds at 32 000 feet agl, and a temperature of 24 degrees Celsius (ºC).

After the accident, the Penticton FSS recorded a special weather observation at 1147. The only changes included a shift in the wind to 320ºT at 5 knots and a temperature of 25ºC.

The weather conditions at Penticton at the time of the accident exceeded the minima required for VFR flight.

1.8 Aids to Navigation

Not applicable.

1.9 Communications

1.9.1 Penticton FSS

The three FSS specialists on duty in the Penticton FSS constituted normal staffing for the time of day. The Downstairs position is the only 24-hour position. When the Radio or Support position is operational, the Downstairs position can monitor the Penticton MF, but normally does not. The position is not directly involved with the traffic activity in the vicinity of the Penticton airport.

The primary responsibility of the Radio position is communication with all aircraft within the Penticton MF area. The FSS MANOPS prioritizes the services to be provided as follows: 1) emergency situations, and 2) in-flight services. In-flight services include airport advisory service (AAS), which consists of the following information, normally in the following sequence:

  1. aircraft traffic (pertinent traffic), including, when known:
    1. aircraft type;
    2. direction of flight, altitude, and the pilot's stated intentions; and
    3. other information to assist aircraft in establishing visual separation;
  2. preferred or active runway (number);
  3. wind (direction, speed);
  4. altimeter (setting);
  5. ground traffic; and
  6. supplementary information.

FSS MANOPS 811.4 states:

  • Provide traffic information updates if you become aware of potential conflicts or unusual circumstances (e.g. poor communications, unfamiliar terrain, requirement to monitor other frequencies, urgent and emergency situations, bilingual communications, etc.).
  • Note 1: Potential conflict is a situation where an aircraft must alter its flight path to avoid another aircraft.
  • Note 2: Traffic information update is any new information since the initial advisory which is essential to the safety of the flight.

The primary responsibility of the Support position is to provide assistance to the Radio position. This duty includes receiving air traffic control clearances from the Vancouver Area Control Centre via land-line and handling telephone calls and faxes related to aircraft and vehicle activity at the Penticton airport. Both positions can hear incoming transmissions on the MF and the ground control frequency.

The responsibilities of the Downstairs position include taking weather observations, providing pilot weather briefings, copying flight plans, providing flight information service en route, providing remote communication outlet services for the Kelowna airport, monitoring navigation aids, and other miscellaneous duties. This position assumes all responsibilities when the other FSS specialist positions are not in operation. FSS specialists may relay air traffic control clearances; however, they are not authorized to issue clearances to aircraft.

The FSS is not equipped with any technology-based aids, except an emergency direction-finding unit, to assist specialists to develop or maintain situational awareness of aircraft positions within the MF area.(2) The direction-finding unit is used in determining the bearing of an aircraft that is transmitting or to provide bearing information to a pilot, if requested.

At the time of this midair collision, the two accident aircraft were the only known air traffic in the MF area, an area of about 80 square nautical miles. These two aircraft had been the only known air traffic in the Penticton area for about three minutes before the collision, that is, since about the time the pilot of the Mooney reported passing the Naramata NDB. Both FSS specialists at Penticton described the workload at the time as light, and communication records show that the FSS had communicated with four aircraft and one staff vehicle in the 11 minutes before the accident.

1.9.2 Pilot Communication Responsibilities

Pilots are required to make a number of standard radio calls and to monitor the MF frequency when operating within an MF zone. The specific radio calls and the associated MF procedures are detailed in section RAC (Rules of the Air and Air Traffic Services) of Transport Canada's Aeronautical Information Publication (AIP). AIP RAC 4.5, Aircraft Operations—Uncontrolled Aerodromes, spans seven pages and refers to a diagram that is eight pages away, in a non-applicable section. Information from pertinent sections of AIP have been included in sections 1.17.5 and 1.17.6 of this report.

1.9.3 Communication Summary

The FSS communication records show that both of the accident aircraft were in two-way communication with the Penticton FSS on the MF during the seven minutes before the collision. A summary of communication exchanges between the pilots of both accident aircraft and the Penticton FSS on the MF follows:

  • At 1129, the pilot of the Mooney was already on the MF. The pilot of the Cessna made initial contact with the Penticton FSS on the MF and advised that he was ready to taxi for a VFR flight to Valemount. The FSS responded with an airport advisory that included a traffic advisory for three aircraft inbound to the airport, including the Mooney, and indicated that runway 34 was the active runway. The pilot of the Cessna acknowledged the traffic.
  • At 1130, the pilot of the Mooney advised the Penticton FSS that he was six miles northeast and proceeding toward Naramata for descent, before joining the circuit for runway 34.
  • At 1133, the pilot of the Mooney reported passing by Naramata and turning inbound to the airport.
  • At 1134, the pilot of the Mooney revised his routing with the Penticton FSS; he now intended to proceed down the west shoreline, remaining west of "the track", and he requested traffic in that area.(3) The FSS advised that there was no reported traffic in that area at the time. The pilot replied that he would report right-hand downwind for runway 34.
  • Twenty-five seconds later, the pilot of the Cessna advised the FSS that he was ready to depart runway 34. The FSS acknowledged, and no other information was exchanged. The pilot of the Cessna then advised that he was rolling and began his take-off.

1.10 Airport Information

The Penticton airport control tower was closed in 1995; AAS is now provided by Nav Canada through an onsite FSS. This change in service was, and remains, a controversial issue in the Penticton community.

The Penticton airport is certificated and operated by Transport Canada. It is located in the Okanagan valley at latitude 49º27' North and longitude 119º36' West, adjacent to the city of Penticton. The city and the airport are on a narrow strip of land that separates Okanagan Lake, to the northwest, and Skaha Lake, to the southeast. The two lakes are connected by a canal that runs through the city. The airport elevation is 1129 feet above sea level (asl) and is served by runway 16/34, which has an asphalt surface 6000 feet long by 148 feet wide and a heading of 161º/341ºM. Runway 34 has a displaced threshold of 300 feet. Canada Flight Supplement states that circuits for runway 34 at the Penticton airport are right-hand. The manoeuvring area is confined by terrain.

In 1995, after completion of a rationalization study, the airport control tower was closed. The tower had been operating limited hours, and the Penticton FSS, which operated 24 hours a day, would provide an AAS when the tower closed for the day. The FSS now provides an AAS at all times. With the closing of the tower, the airport changed from a controlled airport with a positive control zone to an uncontrolled airport with an associated MF area. The Penticton airport is surrounded by a control zone with a radius of 5 nm, extending up to 4100 feet asl. This control zone is designated as Class E airspace, which includes control zones without an operating control tower. This airspace designation allows aircraft operating under instrument flight rules (IFR) to arrive and depart subject to air traffic control clearances without leaving controlled airspace. The Penticton airport is uncontrolled, and IFR and VFR operations are permitted. This same control zone is also designated as the MF area. Position reporting, information from the FSS, and the see-and-be-seen principle are the means employed for traffic separation at uncontrolled airports.

1.11 Flight Recorders

Flight recorders were not fitted in either aircraft, nor were they required to have been.

1.12 Wreckage and Impact Information

The in-flight collision resulted in three separate wreckage sites. After the collision, the inbound Mooney continued briefly along the original direction of flight before descending steeply onto the terrain. The departing Cessna immediately descended steeply, struck the terrain, and burst into flames. The Mooney's vertical stabilizer and a section of each aircraft's right wing landed on the city's waste treatment plant property.

The Penticton NDB tower is 1 nm north of the departure end of runway 34, on the extended runway centreline. The Mooney wreckage site was on a bearing of 132ºM, 1970 feet from the Penticton NDB tower, 4580 feet north of the departure end of runway 34. The Cessna wreckage site was on a bearing of 210ºM, 440 feet from the Penticton NDB tower, 5940 feet north of the departure end of runway 34. The third wreckage site was on a bearing of 162ºM, 1330 feet from Penticton NDB tower.

1.12.1 Mooney M20C

The Mooney struck the ground upright in a steep nose-down attitude in an asphalt-surfaced factory work yard, narrowly missing workers. All flight instruments, engine instruments, and radio equipment were destroyed. No fire occurred at this site. Information gathered from the Mooney wreckage indicates that one communication radio was set to the Penticton MF of 118.5 megahertz. The emergency locator transmitter (ELT) was in a mounting attachment with the switch in the armed position. No ELT signal was received by the Penticton FSS. It was not determined why no signal was heard or if, in fact, the ELT transmitted a signal. The wing flaps and the landing gear were retracted.

At the point of ground impact were the propeller (still intact with one blade scarred and bent), powdered glass from the landing light lens, and impact marks in the asphalt surface from the severed right wing spar. From the point of impact, the wreckage was disbursed predominantly to the east. The front section of the Mooney, ahead of the passengers seats, was found upside-down within 15 feet of the impact point, while the remainder of the fuselage was found 30 º to the right, 50 feet from the impact point. The right horizontal stabilizer showed damage consistent with a propeller blade strike. The damage was from the bottom through the top and progressed from the rear to the front. In addition, the forward, outboard end of the right horizontal stabilizer was sheared off at 40º to the leading edge (when viewed from above, with one side of the angle formed by the leading edge, from the outboard end to the strike mark).

1.12.2 Cessna 177RG

The aircraft struck the ground upright on an easterly heading, in a steep nose-down attitude, in a vacant asphalt-surfaced parking lot, and burst into flames. The wreckage was destroyed by fire except for the empennage. The wreckage site was compact, with minor disbursement of miscellaneous materials. All flight instruments, engine instruments, and radio equipment were destroyed, and no useful information was gathered from them. The ELT was not found, and no ELT signal was received by the Penticton FSS. The wing flap actuator was later recovered; a measurement of extension indicated that the flaps were extended 9º at the time of collision. This setting is consistent with the pilot's operating handbook (POH) recommendation to use 0º to 10º of flap for take-off. The landing gear was retracted.

The propeller hub and one blade were found together under the main wreckage but were not attached to each other. The missing propeller blade was recovered from a field about 550 feet north of the main wreckage.

The separated outboard section of the right wing was recovered from the waste treatment plant property 1100 feet southeast of the main wreckage. It was severely damaged and was found near the separated wing section and vertical stabilizer of the Mooney.

1.12.3 Wing Wreckage Site

The outboard sections of the aeroplanes' right wings were found close to each other at the waste treatment plant. The Mooney's vertical stabilizer was later recovered from one of the treatment ponds at this site. This site is between the two main wreckage sites and is at the west end of Waterloo Avenue, about 1060 feet west of the Mooney wreckage.

The Cessna's wing section, with a piece of the aileron attached only by the control rod assembly, was severely damaged. The Mooney's wing section was relatively intact and showed damage consistent with two propeller blade strikes, both from the bottom through the top. The first strike mark formed an angle of 45º to the leading edge of the wing (when viewed from above, with one side of the angle formed by the leading edge, from the wing tip to the strike mark). It measured 8.5 inches in length and began at 84.5 inches from the wing tip, as measured along the leading edge. The second strike mark formed an angle of 130º to the trailing edge of the wing (with one side of the angle formed by the trailing edge, from the wing tip to the strike mark). This strike mark began in the wing flap, 1 inch aft of the wing trailing edge and 93 inches from the wing tip, as measured along the trailing edge. Combined with the shearing forces of the collision, this strike severed the wing on the outboard side of the main landing-gear wheel well.

The Mooney's vertical stabilizer showed some shearing damage from an unidentified source.

1.13 Medical Information

A review of both pilots' medical records did not provide any indication of prior medical conditions that would have adversely affected their performance. Similarly, the results of the autopsies and the toxicology tests did not indicate the presence of disease or conditions likely to have led to incapacitation or impairment before the collision.

1.14 Fire

The Cessna burst into flames at ground impact and was consumed. The fire was extinguished by the Penticton Fire Department and was contained to the aircraft and a small area of the adjacent field.

No fire occurred at the crash site of the Mooney or at the separate location of the two wing sections and the vertical stabilizer.

1.15 Survival Aspects

The magnitude of the forces experienced by the occupants of both aircraft during this accident was extremely high, well above the levels of human tolerance.

1.16 Tests and Research

1.16.1 Collision Geometry

Vector diagrams of the estimated flight paths of both aircraft before the collision are based on the following information:

  1. The Cessna departed runway 34. The wind was calm. The aircraft maintained the runway heading of 340ºM. The recommended climb speed range is 85 to 100 knots. The landing gear was retracted, and the flaps were extended to 9º. The propeller rotates in a clockwise direction when viewed from the pilot's seat.
  2. The Mooney was flying on a heading of 115ºM at the point of collision, based on a heading of 340ºM for the Cessna and the initial propeller strike angle of 45º to the leading edge of the right wing of the Mooney. Scratches on the bottom of the severed right wing section form an angle of about 18º clockwise from the longitudinal axis of the aircraft, which forms one side of the angle as viewed from above. This angle indicates the combined collision vector of the two aircraft. A diagram of the same vector, constructed by connecting the two measured propeller strikes in the right wing, forms an angle of 16º.
Figure 2 - Collision Flight Paths

Figure 2 - Collision Flight Paths

1.16.2 Cessna 177RG

The take-off and climb performance for the Cessna under the existing weather conditions was estimated from information provided in the POH. Assuming that the pilot flew the aircraft in accordance with the POH, after lift-off he retracted the gear, reduced engine power to 2500 revolutions per minute and 25 inches of manifold pressure, maintained 9º of flaps, and climbed at 85 knots. Under these conditions, the average rate-of-climb would be about 500 feet per minute, and the aircraft would have reached a height of 500 to 700 feet above the airport elevation at the time of the collision. This estimate is consistent with other calculations that were based on witness observations.

1.16.3 Mooney M20C

At a point over the shoreline, abeam the West Bench area, the Mooney turned left and proceeded southeast, almost parallel to the canal. It was not determined if the aircraft was climbing, descending, or maintaining altitude at the time of the collision. Propeller strike damage to the leading edge of the Mooney's right wing indicates an approach angle between the two aircraft of about 45º from the Mooney's right, front quadrant and from the Cessna's left, front quadrant.

The combination of the Mooney's heading and configuration—no flaps or landing gear extended—at the point of collision indicates that the pilot was not intending to land on runway 16 at Penticton. He was told that runway 34 was the runway in use.

1.16.4 Constant Relative Bearing

It is commonly known that a person will visually acquire a moving object more readily than a stationary one. When two aircraft are on a collision course and neither is turning, each has a constant relative bearing to the other. This means that each aircraft, if seen, would appear to be motionless to the other pilot. This apparent lack of motion increases the difficulty of detecting the other aircraft.

1.17 Other Information

1.17.1 Visual Limitations from Aircraft Design

A low-wing aircraft increases the difficulty of visually acquiring conflicting traffic on the high side of the turn because the rising wing and the associated roll of the fuselage impair the sightlines and the reference to the horizon.

1.17.2 Physiological Limitations of the Human Eye

The eye has an inherent physiological defect where the optic nerve, which carries information from the eye to the brain, attaches to the retina. Because this connection point has no photo receptors, each eye has a blind spot, for which the other eye normally compensates. When looking at an object with one eye closed, the image still appears to be complete because the brain paints in a background of colour and texture to hide the blind spot so that there are no holes in the image seen. At a distance of 500 feet, an object the size of a truck can be completely covered by this blind spot.(4)

1.17.3 Midair Collision Defences

Safety in aviation is based primarily on the concept of defences built into the system. Recommended procedures, technical assistance, and communication provide forms of defences and redundancy to reduce the likelihood of a single failure leading to a catastrophic event.

For uncontrolled airports within a mandatory frequency area, the primary element of defence is provided by the principle of see-and-be-seen. The responsibility for seeing and avoiding other aircraft rests with every pilot whenever flights are conducted under visual meteorological conditions. Under certain circumstances, physiological limitations of the eye, angular size of the approaching traffic, cockpit distractions, workload, and numerous other factors may adversely affect a pilot's ability to see approaching traffic.

A second element of defence and redundancy is provided through recommended or mandatory procedures. These procedures are published to encourage commonality of operations. When non-standard procedures are used, especially when they are not communicated, other users of the airspace may not be aware of actions being taken and a conflict may occur.

A third element of defence and redundancy is provided through communication on the MF. This element requires all pilots within a defined area to communicate on a prescribed frequency. Pilots are required to transmit position reports and to maintain a listening watch for position reports from other pilots. This procedure allows pilots to provide their own separation from each other and to organize themselves in a safe and orderly manner. Research conducted by the Lincoln Laboratory during traffic alert and collision-avoidance system (TCAS) flight testing showed a 50 per cent improvement in the visual target acquisition rate by pilots alerted to the presence of other aircraft, and the median range of visual acquisition improved by 40 per cent.(5)

The provision of an FSS provides a fourth element of defence through redundancy by requiring all pilot transmissions within the MF area to be directed to the FSS, thereby placing a third party in the communication chain. The responsibility of the FSS is to provide an AAS that includes the dissemination of traffic information pertinent to the existing conditions.(6) An FSS provides advisory information only and is not responsible for air traffic control or traffic separation.

1.17.4 Statistics

According to Transport Canada, FSSs were in operation at 78 Canadian airports at the time of the occurrence. FSSs provided remote AAS to 36 additional airports. However, FSSs do not provide AAS for airports with 24-hour control tower service.

Nav Canada gathers statistical information regarding loss-of-separation and risk-of-collision events involving aircraft operating under IFR within controlled airspace. A meaningful comparison, however, cannot be made to the number of the same events that may occur in uncontrolled airspace because records are not kept of the number of aircraft operations in uncontrolled airspace. Information available does indicate that in 1998 there were 2 351 312 aircraft movements (a take-off or a landing) at Canadian airports not served by an operating control tower. In the 10 years preceding this accident, 17 midair collisions occurred. Of these accidents, 8 involved some form of formation flight, 3 occurred in practice training areas, and 6 occurred in the vicinity of uncontrolled airports between aircraft that were not associated with each other. None of these accidents occurred within the control zone of airports where air traffic control was providing an advanced level of service (that is, with an operating control tower or where an FSS was providing an AAS).

1.17.5 Circuit Procedures—Uncontrolled Aerodromes

Rules and procedures pertaining to circuits at uncontrolled airports are widely distributed by Transport Canada and form the basis for safe manoeuvring in the vicinity of aerodromes.

AIP RAC 4.5 prescribes the procedure that pilots are required to follow when operating at an uncontrolled airport. Rules applicable to this occurrence have been excerpted from RAC 4.5:

  • 4.5.2 Traffic Circuit Procedures—Uncontrolled Aerodromes
  • The following procedures apply to all aircraft operating at aerodromes where airport control service is not provided except those aircraft following a standard instrument approach procedure. . . . Prior to joining a traffic circuit, all pilots should announce their intentions. . . . All turns shall be to the left while operating in the circuit, unless a right-hand circuit has been specified in the CFS [Canada Flight Supplement]. . . .
Figure 3 - Standard left-hand circuit pattern

Figure 3 - Standard left-hand circuit pattern

NOTES:
  1. The circuit is normally flown at 1 000 [feet] AAE [above aerodrome elevation].
  2. If a right-hand circuit is required in accordance with CAR 602.96, the opposite of this diagram is applicable.
Joining the Circuit
  1. . . . When joining from the upwind side, plan the descent to cross the runway in level flight at 1 000 [feet] AAE or the published circuit altitude. Maintain that altitude until further descent is required for landing. . .
  2. Aerodromes within an MF area when airport advisory information is available:
    1. Aircraft may join the circuit pattern straight-in or at 45º to the downwind leg or straight-in to the base or final legs (Figure 4.1). Pilots should be alert for other VFR traffic entering the circuit at these positions and for IFR straight-in or circling approaches. . . .
Departing the Circuit or Airport
  1. Aircraft departing the circuit or airport should climb straight ahead on the runway heading until reaching the circuit traffic altitude before commencing a turn in any direction to an en route heading. Turns back toward the circuit or airport should not be initiated until at least 500 [feet] above the circuit altitude.

The circuits for runway 34 at the Penticton airport are right-hand. Therefore, the procedure described in AIP is opposite.

1.17.6 Communication Procedures—Uncontrolled Airports

AIP RAC 4.5.4 and 4.5.7 prescribe the communication procedures pertaining to an airport where an MF is in effect:

4.5.4 Mandatory Frequency

. . . Reporting procedures shall be followed, as specified in CARs 602.97 to 602.103 inclusive. An MF area will be established at an aerodrome if the traffic volume and mix of aircraft traffic at that aerodrome is such that there would be a safety benefit derived from implementing MF procedures. . . . When a ground station is in operation, for example, an FSS, . . . then all aircraft reports that are required for operating within, and prior to entering an MF area, shall be directed to the ground station. . . .

4.5.7 VFR Communication Procedures at Uncontrolled Aerodromes With MF and ATF Areas
  1. Radio-Equipped Aircraft

    The following procedures shall be followed by pilots of radio-equipped aircraft at uncontrolled aerodromes within an MF area and should also be followed by pilots at aerodromes with ATFs:

    1. Operations on Manoeuvring Area

      Report intentions prior to entering the manoeuvring area, and maintain a listening watch on the MF or ATF frequency while operating an aircraft on the manoeuvring area. (CAR 602.99)

    2. Departure
      1. Complete pre-takeoff check, and report departure intentions on the MF or ATF frequency before moving onto the runway. If a delay is encountered, broadcast intentions and expected length of delay; . . .
      2. Ascertain by radio on the MF or ATF frequency and by visual observation that no other aircraft or vehicle is likely to come into contact with the aircraft during takeoff; and
      3. Report departing from the aerodrome traffic circuit, and monitor the MF or ATF until well clear of the area (5-10 NM). (CAR 602.100) [Added to regulation April 2001.]
    3. Arrival
      1. Report position, altitude, arrival procedure intentions and estimated time of landing at least 5 minutes (where possible) prior to entering the area;
      2. Maintain a listening watch on the MF or ATF while in the area;
      3. Report joining the circuit pattern giving position in the pattern;
      4. Report on downwind leg, if applicable;
      5. Report established on final approach; and
      6. Report clear of the active runway after landing. (CAR 602.101) . . .

2.0 Analysis

2.1 General

This accident can be described as a "non-associated midair collision".(7) This means that the pilots involved were not intentionally flying in close proximity as they would if they had been involved in a formation flight. Given the circumstances of this accident, it is likely that, although each pilot was probably generally aware of the other—through radio communications—neither one was specifically aware of the location of the other aircraft. During the investigation into this accident, no mechanical defect with either aircraft was found, nor was there any indication of pre-existing disease or conditions likely to have led to the pre-impact incapacitation or impairment of either pilot. To address the issues of why these two aircraft were in each other's vicinity without knowing the other was there, this analysis will examine airport traffic circuits, circuit-joining procedures, communication procedures, and the see-and-be-seen principle. Rules and procedures that address right-of-way issues are not discussed in this report because they cannot be applied to non-associated collisions; that is, one cannot be expected to give way to another if one is not aware of the other. Weather is not considered a contributing factor in this accident.

2.2 Circuit Procedures and Communications Procedures

2.2.1 Mooney M20C

When the Mooney passed by the Naramata NDB to return to the airport, the pil